Segment Information - Components of Segment Revenues and Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Segment Revenues	$ 73,766	$ 57,401	$ 134,797	$ 108,355
Segment Adjusted EBITDA	13,895	8,538	19,448	13,610
Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	73,766	57,401	134,797	108,355
Segment Adjusted EBITDA	18,979	12,380	30,088	20,983
Assessment, Permitting and Response | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	18,631	5,028	23,161	9,603
Segment Adjusted EBITDA	4,989	2,002	6,431	3,996
Measurement and Analysis | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	37,036	34,617	73,476	62,948
Segment Adjusted EBITDA	11,615	7,979	19,176	12,112
Remediation and Reuse | Operating Segments
Segment Reporting Information [Line Items]
Segment Revenues	18,099	17,756	38,160	35,804
Segment Adjusted EBITDA	2,375	2,399	4,481	4,875
Corporate and Other
Segment Reporting Information [Line Items]
Segment Adjusted EBITDA	$ (5,084)	$ (3,842)	$ (10,640)	$ (7,373)